How Does a Flex PCB Manufacturer Handle Changes in Project Specifications?
Flex PCB Manufacturer Handle Changes in Project Specifications
If you’re building a flex PCB, it’s important to be aware of how your manufacturer will handle changes in project specifications. The manufacturing process is quite different for flex circuits and it’s essential to follow IPC rules to ensure that you get the best quality product possible.
Unlike rigid PCBs, a flex circuit is made of multiple layers of materials including copper-clad laminate (CCL), dielectric, solder mask, and coverlay. These materials must work together to meet your specific electrical, mechanical, and environmental requirements.
The CCL is the foundation of a flex pcb manufacturer and serves as an insulation layer that protects it from corrosion, high temperatures, and other extreme conditions. It also helps keep the flex circuit from softening during soldering and reduces the likelihood of via breakage. A flex PCB’s layers are attached to the CCL using either adhesives or a special base material. Most manufacturers prefer to use a polyimide resin as it’s superior in thermal control and provides a higher level of reliability.
How Does a Flex PCB Manufacturer Handle Changes in Project Specifications?
The plated copper on the flex PCB is another key factor in its reliability. For example, flex circuits typically use the Pad Plate method of plating which limits plated copper to the pads and surrounding area. This prevents the plated copper from coming into direct contact with the conductor traces, which could compromise the mechanical bendability of the flex circuit and result in broken traces or pad damage. Rigid PCBs, on the other hand, use a Pattern Plate plating method which plates copper throughout the entire surface of the circuit.
Another critical factor in a flex circuit’s durability is the choice of solder mask and coverlay. Most manufacturers use a photoimageable solder mask and an additional polyimide film to protect the flex circuit’s outer surfaces from corrosion and damage. The coverlay is then laminated to the flex circuit and cut to shape. Depending on the design, certain areas may require stiffeners which are strips of rigid material like FR4 or polyamide that are added to selected sections of the flex circuit to provide additional strength and mechanical stability.
For applications that are particularly sensitive to electromagnetic interference (EMI), a shielding film can be applied to the flex circuit. This will help to reduce noise and improve signal timing by preventing the transmission of electromagnetic energy from one section of the circuit to another.
Lastly, pressure-sensitive adhesives, also known as PSAs, can be used to attach components to the flex PCB before it’s assembled. This is an effective way to secure the components in place without soldering them, and it’s easy to apply. This technique also allows for easier assembly and removal of the flex circuit from its mounting surface. For a more permanent attachment, a different type of bonding material is required, such as an epoxy adhesive or a hot-melt glue. This will allow for greater flexibility and longevity. However, this technique may increase the production cost.